Minimally-invasive surgical techniques, such as thoracoscopy, laparoscopy, pelviscopy, endoscopy, and arthroscopy, minimize patient trauma by providing access to interior body cavities through very small incisions or through percutaneous cannulas known as trocar sleeves. To perform a surgical procedure, elongated, low-profile instruments are introduced into a body cavity through these incisions or trocar sleeves. Visualization is facilitated by percutaneous visualization devices known as laparoscopes, endoscopes, arthroscopes, and the like, which typically consist of a video camera configured for introduction through a small incision or trocar sleeve to allow observation of the body cavity on a video monitor. By obviating the need for a large, open incision to expose the body cavity, minimally-invasive techniques can significantly reduce the pain, recovery period, morbidity and mortality rates, and cost of open surgical procedures without a sacrifice in efficacy.
In recent years, minimally-invasive techniques have been developed to facilitate the performance of a variety of surgical procedures on organs and ducts of the abdominal and pelvic cavities. Well-known examples of such procedures include laparoscopic cholecystectomy, laparoscopic appendectomy, laparoscopic hysterectomy, and laparoscopic hernia repair.
A particularly important milestone in minimally-invasive surgery has been attained with the development of thoracoscopic techniques for surgery of the heart and great vessels. Such techniques are described in co-pending, commonly-assigned U.S. patent application Ser. No. 08/023,778, filed Feb. 22, 1993, the complete disclosure of which is hereby incorporated herein by reference. In that application, thoracoscopic techniques for performing coronary artery bypass grafting (CABG) are described which eliminate the need for the sternotomy or other tom of gross thoracotomy required by conventional, open surgical techniques. In thoracoscopic CABG, an arterial blood source such as the internal mammary artery (IMA) is dissected from its native location, transected, and prepared for attachment to an anastomosis site on a target coronary artery, commonly the left anterior descending coronary artery (LAD). A portion of the target coronary artery containing the anastomosis site is then dissected away from the epicardium, and a small incision is made in the arterial wall. The distal end of the arterial blood source (e.g. IMA) is then anastomosed over the incision in the target coronary artery, usually by suturing. Each of these steps is performed by means of instruments introduced through small incisions or trocar sleeves positioned within intercosial spaces of the rib cage, under visualization by means of an endoscope or other percutaneous visualization device.
Because the CABG procedure requires complex microsurgery to be carded out on extremely small body structures, surgical instruments designed for laparoscopic and other minimally-invasive applications are not generally suitable for performing thoracoscopic CABG. Most laparoscopic procedures, for example, target body structures which are quite large in comparison to the coronary vessels, and do not require the high degree of precision required by microsurgeries such as CABG. Accordingly, laparoscopic instruments generally have relatively large end-effectors with relatively large ranges of movement, making such instruments ill-suited for use on very small structures like the coronary vessels. In addition, such instruments commonly have finger loops or pistol-type actuators gripped in the user's palm or between the user's thumb and forefinger, limiting the sensitivity and precision with which such instruments can be manipulated and actuated. Such finger loops or pistol-type grips also are limited to a single orientation in the user's hand and cannot be repositioned in the hand to allow better access to a body structure or to change the orientation of the end-effector.
The advent of thoracoscopic CABG and other minimally-invasive microsurgical procedures therefore demands a new generation of microsurgical instruments specifically designed to meet the unique needs of such procedures. These instruments must have a small profile for introduction through small incisions or trocar sleeves, and a length sufficient to reach the heart and other thoracic organs and vessels from various percutaneous access points. The instruments must have end-effectors adapted to perform delicate, high-precision microsurgery on very small vessels, including end-effectors having very small dimensions and very short ranges of motion. The instruments must have actuators that facilitate ergonomic, one-handed actuation with sensitivity and precision, preferably having a stroke which is large enough for comfortable actuation by the fingers and which is reduced to a very short range of motion at the end-effector. Desirably, the actuators will have a configuration which is analogous to surgical forceps or to other types of microsurgical instruments commonly utilized in open surgical procedures, shortening the learning curve required for adoption of minimally-invasive microsurgical techniques.